I am newbie trying to generate a part with a curve central line (path) but different shapes of the cross sections at both ends. I figure out that if I can assign proper guidelines then I can do a sweep to get this done. But the guidelines are not easy to draw, too.

So I post my question here. I wish somebody can show me how to do this step by step. Thanks very much in advance!

Description of the desired part:

The central line is a curve. It could be a spline.

The cross sections have a similar lenticular shape (two identical arcs combined together). And two typical shapes are given by the chord length a and the rise length h.

The path can be treated as three sections:

the first third of the part has a constant cross-sectional shape with a=0.8 and h=0.07

the middle section of the part has a gradual cross-section

the last third of the part has a constant cross-sectional shape with a=0.4 and h=0.13

The cross-sectional area need to be kept constant as possible.

I am really new to Solidworks. So step by step instruction is truly important for me to follow. But even some hints are helpful to me so I can try them one by one.

I am newbie trying to generate a part with a curve central line (path) but different shapes of the cross sections at both ends. I figure out that if I can assign proper guidelines then I can do a sweep to get this done. But the guidelines are not easy to draw, too.

So I post my question here. I wish somebody can show me how to do this step by step. Thanks very much in advance!

Description of the desired part:

The central line is a curve. It could be a spline.

The cross sections have a similar lenticular shape (two identical arcs combined together). And two typical shapes are given by the chord length a and the rise length h.

The path can be treated as three sections:

the first third of the part has a constant cross-sectional shape with a=0.8 and h=0.07

the middle section of the part has a gradual cross-section

the last third of the part has a constant cross-sectional shape with a=0.4 and h=0.13

The cross-sectional area need to be kept constant as possible.

I am really new to Solidworks. So step by step instruction is truly important for me to follow. But even some hints are helpful to me so I can try them one by one.

Best regards,

Haoxian

From your description I'd suggest two separate Sweeps, one for each end (the constant cross-sections), and connect them with a Loft.

I finally can implement your approach on last Friday. But the problem is that if I draw the whole path first, the first sweep will be on the whole path, too. That means I can only construct the part segmentally, then merge the sub-parts together to get a complete part. Is there any way I can draw the path completely first then do sweep, loft and sweep operation section by section? Sorry for that I know my question is so low.

You could do this via one loft feature. Create points at 1/3 length from both sides. Then use them to create new planes. Finally you can add derived sketches on those two planes. This would keep the derived sketches same as original sketches. Finally loft all those 5 sections

The other option would be 3 features like Glenn mentioned. You can split the guide curve/path into 3 parts and then use them for sweep and loft.

Thank you very much for your additive message. It seems a really great idea to make this part in one loft feature. I really love that. Will try it tomorrow.

Could you explain in detail on how to "add derived sketches on those two planes"? I am really fresh-hand on this. I mean, the sketch of cross-section on the first plane is exactly the same as that on the start plane, so do we have a short-cut to make the sketch?

Haoxian, sorry but I stand wrong. Without the additional guide curves or settings in the loft feature, it might not be easy to achieve the desired results. But yes derived sketches are quick to create. Check attached video showing the steps.

Thank you so much for this video. It is very clear. The only difference between my problem and that in your video is that the central line in my case is a curve. I guess your approach would work for me. I havn't try this yet because I am busy in doing other stuff today.

I think you are right about this. In my case, I don't want to draw a guideline because it's very difficult to calculate. There is only a central line as path. So for this case, if two middle planes are created and derived cross sections are made, there sweep/loft features are greyed out in the toolbar. That it works in your video might because you used a straight line as the central path.

I guess I have to make three parts then combine them together. But the difficult is to align them precisely when assembling these parts because the parts are not straight along the path.

Do you happen to know some tricks about doing this? I tried the "mate" operation, but I can only get the end face of first part and the start face of the second part to align parallelly but not coincidently.

You can actually do everything in one part three features like Glenn has mentioned.

Create two references points on the path (you might have to split the path into three segments). Create planes at the two points. Now sketch your profiles on those two plane and loft using center-line option. Finally sweep the two profiles picking the remaining paths .

Thank you very much. I managed to create 3 parts as suggested and merged them together to get the result I wanted. Two of the parts are created by sweep and one of them is created by loft along a center-line.

I tried to finish this in one part. But the when I selected the central line for the sweep, it would sweep from the start point to the end point of the whole curve. I do not know how to select the first several sections of the curve as central line (the curve is already splitted into a few segments because it is constructed by a few arcs).

For assembly purpose, I constructed the whole central line first saved as a template. And copied it as part 1, part 2 and part 3. Then editted those three parts individually by turning the not-needed-part of the curve into construction feature. After this, I could make the sweep, loft and sweep respectively. When assembling these three part, they could fit exactly to adjacent parts as the original central line guided because the default option of adding a new part was to use the original coordinates of the part.